15% Rule
Recorded detail
kVp
Image Sharpness
Random
100
Which factor(s) will be adjusted when maintaining density?
kVp and mAs
100
What is the degree or amount of geometric sharpness of an object recorded as an image?
Recorded detail
100
What controls the penetration ability of the x-ray beam?
kVp
100
True or False: Imaging systems with better resolution can resolve more line pairs per millimeter
True
100
What is the distance between the x-ray source or focal spot and the image receptor called?
SID(source to image receptor distance)
200
What is the equivalent of increasing the kVp by 15%?
Doubling the mAs (changing mAs by a factor of 2)
200
Name two alternate names for recorded detail.
Definition, Sharpness, Spatial Resolution, or Detail
200
True or False: An increase in kVp results in a decrease in exit radiation, explain your answer.
False, results in an increase of exit radiation
200
What is the degree of sharpness or spatial resolution determined by?
Line pairs per millimeter (lp/mm)
200
When are larger mA values with shorter exposure time used?
When attempting to decrease patient motion
300
What is the equivalent of decreasing the kVp by 15%?
1/2 mAs (decreasing mAs by a factor of 2)
300
Name the two primary geometric factors that govern the appearance of a radiographic image
Recorded detail and Distortion
300
How will density and contrast change with a decrease in kVp?
Density decreases, Contrast increases
300
What is another name for the line pair test pattern?
Bar phantom
300
A radiograph is taken at 40" using 72 kVp and 32 mAs. What new mAs is needed to maintain density if the SID is changed to 72"?
mAs = 104
400
A radiograph of the forearm is produced using 4 mAs at 55 kVp. What kVp would be required to halve the exposure?
46.7 kVp (47)
400
Name the two primary photographic factors that govern the appearance of a radiographic image
Density and Contrast
400
How will density and contrast change with an increase in kVp?
Contrast decreases, Density increases
400
What is defined as the smallest separation of two lines or edges which can be recognized as separate structures on the image?
Detail
400
An x-ray exposure of 30 mR is recorded at a distance of 80". What will be the intensity if the distance is changed to 36"?
148 mR
500
True or False: Mammography utilizes a higher kVp to increase the subject contrast of the breast tissue.
False, utilizes lower kVp
500
What are the differences between high and low contrast?
Low contrast: Many shades of gray, High kVp, Long-scale High contrast: Few shades of gray, Low kVp, Short-scale
500
Besides mAs and kVp, what are the four other factors that affect the appearance of the final diagnostic image?
Distance, Focal Spot size, Tube angulation, and Positioning accuracy
500
Define the Reciprocity Law.
Any combination of mA and time with the same mAs will produce the same density/exposure.
500
What is the range of milliampere (mA) selections on modern day x-ray generators?
25 to 1,000 mA
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